Telephone system



Oct. 28, 1924. 1,513,171

J. E. HILBISH TELEPHONE SYSTEM Filed June 20. 1921 T ZZZ/5277017 relay of the first cord in the already estab I Patented Get. 28, 1924.

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JOHN E. I-IILBISH, orLA enANeniLLmoIs, nssrenon TO KELLOGG swI'ron oARn AND surrLY COMPANY, or crrroeeo, rLLI'noIs, Aconroaarron or ILLINOIS.

TELEPHONE sYs'rE vr;

im utation filed June 20,1921. serie 'no; 479,784. A j

To all whom it may concern:

Be it known that I, JOHN E. HILBisH, a citizen of the United States of America, resident of La Grange, county of Cook, and State of Illinois, have invented certain new and useful Improvements'in Telephone Systerns, of which the following is a specification.

My invention relates to telephone systems and has to do more particularly with cord circuits provided with automatic ringing and listening, secret service and instantaneous disconnect and recall, andfit is an object of my invention to provide a circuit of the above class which is highly efiicient in its operation and in which the subscribers that are interconnected for conversational purposes by means of the cord circuit are provided withabsolutely secret service.

In systems of the above character the operator, after establishing a connection, can not listen in on the conversation. This provides secret service, but this secrecy is limited, as it is possible for a'third party to be cut in on theexisting connection.

Should a third party desire to converse with the called subscriberthat is'alr'eadyin conversatiomthe operator tests the multiple jack of the line wanted, The wanted line tested is busy, but should the operator pass over the busy test and insert the calling plug of a second cord circuit into the multiple jack of the busy line, the connection thus will cut in the third party on the existing connection, and he may, therefore, listen in. In addition to permitting eavesdropping, should an operator wish to connect athird party to an existing connection for this ex press purpose, confusion 1s also created when disconnection takes place'when a'third party-is thus connected, and the feature of secret service is destroyed to a certain extent. 5 e

To overcome these objections and limita'- tions of the above classof circuit Ihave designed a circuit, a featureof which is the provision of a relay provided with high and low resistance windings, and which relay, when placed in circuit in establishing a connection closes a low resistance path through itself. A similar relay ofa 'second cord is prevented from operating, due to this low resistance shunt established by the lished connection. The failurerof'the relay of the second cord to operateprev'ents means from operating to efiectively connect athircl party in on the conversation. Should a A third: party attempt toic all a calling party that is already in, conversational circuit, a relay similar to the one "justpointed out acts in the same manner to prevent the relay of the second cord from operating and this prevents the third party from being cut in on the existing connection. f i

For a more complete understanding of my invention, reference may be had to the accompanying drawing, in which I illustrate diagrammatically a telephone system embodying my invention. 1

Referring now in' general to the circuit arrangement as illustrated in the drawing, I show a calling substation A connecting at the exchange with a line circuit L, whichincludes a line relay LR, a cut-off relay CO,

multiple jacks J and the multiple line lamps S, appearing in, the different. operators positions in' theexchangeswitchboardfi The COI'ClClI'Cult C for interconnecting subscribers. substations as calling and called lines comprise ananswering plug AP and a calling plug 5GP, the said answering plug AP and 'the'callin'g plug GP beingconnected by the heavily. marked talking conductors and having condensers interposed. Associated with the answering endof the cord circuit:

C is an answering sleeve supervisoryrelay AS and an answering tip supervisory relay AT for controlling the circuit of theanswerking super-visory lamp AL, and the said relay AS also acts'as a test relay for controlling .the connection of the 'operators set 0, to the talking conductors of the cord circuit C.

A linkldisconnectrelay LD is'also associated with the answeringfend ofthe cord circuit C and provides the cord circuit G with ,in-

stantaneous. disconnect and recalliqAssloci? ated. withthe calling end of the cord circuit C is'a calling tipjsupervisory relay CT; and l a calling sleeve supervisoryfrelay CSfOI? controlling the circuit ofthe'calling super lineringing key} RK is" provided for "connectii'igone of a "plurality-of generators G,

G, Gr and. G tothecommonfringing 0011- visory lamp GL5. Th i g sleeve suPerductor RG. A ringing control relay RC is P vided wh ch .cell s th appl t of ringing current, and the relay {RC upon energization connects the constantly rotating interrupter I in circuit with the ringing interrupter-relay RI, said relay RI being inovuith the cord circuit C is a service neter deviceicon prising ,the meter nagnet MM and the ne'terceontrol relay To the right of the ,drawing 1 have shown cacalled substation Btsin ilarzto the substation A,. said substation B connecting at the exchange w th a llnec rcugit L comprising the -.e ecs relay CO, line relay LR, multiple acks J .andniultiple line signals S,

I Having described ingeneral the apparatus embodying my invention, 1 will ,now :describe more in detail the operation of the circuit as illustigated.

Assuming now that the subscniber at the substation A initiates a call, the removal of the receiver by the subscriber at the sub station brings about the energization of ,the line relay LB, and the closing of its alternate contact 2 lights the multiple line signals S at the diflerent operators posh trons. Anridle operator noting the glowing of the line signal S before her position inserts an answering ,p lug A? of the cord circuit C intothe multiple jack Jiot the calling line in her position. The insertion of the answering plug AP into jack J closes a series energizing circuit for the answering sleeve supervisory relay AS of the cord circuit C and the cutofi relay Q of the line circuit iL, this circuit extending from battery through the windings 3 and 4c of the answersleevesupervisory relay AS,.conductor 5, normal contact. '6 of the link disconnect relay LD, sleeve contacts of the connected plug AP and jack J, to ground through the wind lng oi the cut-off relay CO. The relay AS energizing closes, providing the cord circu t C, is the first cord to be connected to the line circuit L. A shunt is placed about the high resistance Winding {i of the relay through its alternate contact 7, thus placing the low resistance winding in cir- .cuit with the cuteofi relay CO, from bat- .tery through the winding of the relay 3, its

{alternate contact 7, over the conductor 5 to ground at the cut-off relay CO, over the prev ouslydescribed path. The relay GO also energ zes over this circuit and upon energiz ng opens-the circuit through the line pelay and the line relay LR d6B11 61giZ mg ere-1 its alterna e con act 2, fa ng the nultlple hue signals S, The relay AS energlziug else c es s i altma cont 8 and 9 t9 eminent the operators Set 0 t he inal cont act 20.0213 the are-lay LD, ring contacts of the connected plug AP and jack .J, through the closed contacts of the substation switchboard and back through the tip contactsof theiconnectedijack J and plug A l normal contact 21 of the relay L1),

conductor 22, alternate contact 18 of the .re-

lay AS, conductor 23, to ground through the lower winding of the relayAT. The relay 7 AT energizing opens its normal contact 24, preventing lighting of the answering supervisory lamp AL at this time. The closing of alternate contact 25 of the relay AT establishes an energizing circuit for the meter relay MR, traced from battery through the winding of the meter relay MR, alternate contact 25 of the relay AT, conductor 26, to

ground at normal contact 27- of the calling sleeve supervisory relay CS. The meter relay MR energizing closes its alternate contact '28, closing an energizing circuit for the meter magnet MM and the ina znet MM energizing actuates the service meter to register a completed answer. 1 i-Sl ould another operator insert an answering plug AP of .a. second cord into a multiple jack of the calling line atter the first operator associated with the cord circuit C has answered the call, the operator of the second cord would not :be connected as no etlective energizing circuit isiestablished for the answering sleeve supervisory relay A55 oi": thesecond cord, due to the low resistance path through the winding .3 of the answering sleeve supervisory relay AS ot' the first cord circuit C, connected to the call ing line. The relay AS in the second cord does not energi;ze for the above reason, and the operators set- 0 is, therefore, not connected to the cord conductors, and the second operator receiving no response withdraws the answering plug AP from the multiple jack of the calling line,

The operator associated with the cord circuit C having been connected to the cord conductors as before described, now inquires the wants of the calling subscriber at the substation A, and assuiningthat it is the subscriber at the substation B that is wanted, the operator tests the called line in the usual manner as to its idle or busy condition by touching the tip of the call-ing plug GP to the sleeve of a multiple jack J associated all) with the called line B and it the said line is husy the operator Will receive the, customary busy click in her head receiver.

Assuming that the line called is idle, the operator Will insert the calling plug Cl into the jack J or" thecalled line, which insertion closes a series energizing circuit for the calling sleeve supervisory relay CS and the cut-oii' relay C@- of the line circuit L over a circuit traced from battery through the windings and 31 of the relay CS, conductor 32, sleeve contacts of the connectedplugCP and jackiJ to ground through the Winding of the cut-off relay CO. alternate contact 33, Which places the lower resistance winding 30 of the sleeve super-V visory relay CS in series with the relay C0 of the line circuit L, the circuit of the relay CS noW being traced from battery through the lower Winding 30 Which \vind ing is of low resistance, its alternate contact 33 and over conductor 32, to ground through the Winding of the cut-oli relay CO, and this low resistance series circuit for re lay CS and relay CO, shunts the high resistance Winding 31 of the said relay CS for purposes as Will be presently described.

The opening of normal contact 27 of the relay CS opens the energizing circuit of the meter relay MR, and the meter relay MR cle-ei1ergizing prevents further registration of the service mete The opening of normal contacts 14 and 15 of the relay US the cord conductors, and the closing of alternate contact 27 of the relayfCS estab lishes an energizing circuit for the secondary calling sleeve supervisory relay CS,

traced from battery through the Winding of the relay CS, conductors-35 and 36 to ground at alternate contact 27 of the relay,

CS, and the said relay CS energizing its alternate contact 80 is closed closing the tipcord conductor and the further purposes of the relay CS Will he presently'described in detail. v c r V The closing of alternate contact 2'1 also called for subscriber at substation .B, and

the lamp CL only remains lighted until the operator depresses the ringing key BK to.

apply ringing current.

The operator now 7 depresses one of" the ringing key plungers of ringing key. RK

The relay CS. energizing closes its,

disconnects the operators set 0 trom' to connect one ofthe ringing generators G", G or G to the common ringing conductorjRG: to initiate the operation of the automatic ringing equipment. The operation of the end spring 42 of the ringing key BK when thelplunger is depressed closes circuit for, the interrupter relay RI from 2 battery, through the upper, Winding 43 or the relay RI, conductor 44, through the incinent-arily closed end spring contact a2, conductors 38' and 45, normal contact 39 of the relay Li) conductor 4:0, normal contac-t'tl ofthe relay CT, to ground at altern'ate contact 27 of the relay CS. The relay RI energizing connects --tl1e selected generator, which awe Will assume is generator G, to the common ringing conductor KG, the circuit being tracedfrom the ungrounded pole,

of the generator G, through alternate contact 46 of the depressedringing key plunger, over the common ringing conductor RG, alternate contact 17 of the relay R1, tip contactsxotthe connected plug GP and jack J through the condenser and call. bell at the c-alled substation B, back through the ring contacts of the jack J and plug GP,

to battery and ground. through thefalternate contact 48 or the relay RT. This flow of ringing current from; the 'generato-ri'G insures a ring of the call bell at th called substation the instant 1 thefringing key BK is depressed. The relay RI energizing closes its alternatecontact 49, establishingan energizing circuit for theringing control relay BC, traced from battery, through the Winding of' the relayRC, conductor 50, alternate contact 49 lot therelay RI. conductors 33 and 45, normal" contact 39 of the. relay LD, conductor 40, normal contact 41 of therelayCT, conductori36 to ground at alternate, contact 27 of the. relay CS.

The relayRC energizing closesa locking circuit for itself, traced from ha'tterv throughthe winding of the relay RC, itsi alternatefcontact,37, conductors 38 and 45 normal contact 29 of relay LD, conductor 40, normal contact 4-1 v of relay CT, conductor 36, to ground at: alternate contact 27 of thea'elayGS', andthe relay RC energizingits normal contact'37 is opened to ettace the calling supervisory lainp" CL.

The closureot alternate contact 51 of the relay RC connects the constantly rotating interrupter :1 in circuit with the ringing interrupter relay R1. traced from battery throughthe' lovver Winding 52 of the relay BI, over conductor t 3gzthrough alternate contact 51-of the relay RC, conductor 54-, co ground through theconstantly rotating interrupter I; i, The ringing control relav BI is tl iusintermittently energizedand deenergiz'edto connect; ringing current over the previously described path'to operate the call bellatthe called subscribens substaiii A further result due to the intermittent closure of alternate contact of relay HT is the connection cl anaudible ringing tone to the calling subscribers line, through. alternate contact of the relay to indicate to the calling subscriber that tie call bell at the called substation is being rung.

Upon response or the called subscriber at the. substation B, circuit is closed through its calling tip relay CT. traced from batter; through the lower winding oz? the re 43 cl, normal contact 455 of the relay when the said relay HT is inone ol its ale-energized positions. tl'irough the ring contacts of connected plug Cl and jack 5, through now closed contacts at the substation switchhoolr at substation B, back through the tip contacts of the connected plug P and jack J, normal contact 4;? of the relay Bl, alternate; contactof the sleeve relay CS, conductor 61, to ground through the upp r winding of the relay CT. 7 The relay CT energizing opens the locking circuit of the ringing control relay RC at its normal contact 41, thereby preventing further applications of ringing current to the called subscribers line, due to the openi. of its alternate contact 51, which. disconnects the interrupter T from the ringing interrupter relay RT. The relay RC de-energizing closes its normal contacts 62 and 63, which closes the talking strands of the cord circuit C, and the calling substniber the substation A; and the called subscriber at the substationlB are now in conversational circuit. Said talking circuit may now be traced over the heavily marked conductors.

Assuming now that conversation has terminated, the subscriber at the substation 'A replacing his recelver upon the switchhook opens the energizing, circuit of the answering tip supervisory relay AT, and relay All. deenergizing closes its normal contact 2e, closing a circuit for the linlcdisconnect relay 7 LD, traced from battery through the winding of relay Ll), normal contact 2% of the relay AT, alternate contact T5 of the answering sl eve supervisory relay AS, conductor 36, to ground at alternate contact 2? ot the relay CS. The relay LD energizing opens the series energizing circuit for the answering sleeve supervisory relay AS of the cord circuit C and the cutoff relay CO of the line circuit L at its normal contact 6. The closing of alternate contact 6 of therelay Ll) establishes a substitute holding circuit "for the answering sleeve supervisory relay AS, traced from battery through the lower winding 3 ot the relay AS, its alternate contact '7, conductor 5, alternate contact 6 of the relay Ll), alternate contact 75 ot' the relay AS, concuctor 36, to ground zit-alternate contact of the relayCS. The relay AT {lo-energizing also closes a circuit for the answering superlamp AL, traced from battery h the lamp AL, normal contact 24L of relay AT, alternate contact 75 of the relay 21S, conductor 36, to ground at alternate contact 27 of the relay CS. A further --'esult due to the energizations of the lin; disconnect relay Ll) is the opening of its normal contacts 20, 21, disconnecting the tip and ring conductors of the cord circuit C from the tip and ring conductors of the jack J, thereby operatively dissociating the calling subscribers line from the cord circuit C.

The called subscriber B replacing his receiver on the switchhook opens the circuit of the calling tip supervisory relay CT at the substation switchhook contacts, and

relay CT upon restoration closes its normal contact n establislnng a clrcuit for the callingsupervisory lamp CL, from battery through the lamp CL, conductor 76, alternate contact 89 of the relay Ll), conductor l0, normal contact ll ot' the now deenergized relay CT, to ground at alternate contact :27 ot the relay CS. The operator noting the glowing '01? the answering supervisory lamp AL and the calling supervisory lamp CL, removes the answering plug'AP of the jack J and the calling plug CP o1"- the jack J. The withdrawal of the plug CP opensthe series energizing circuit forthe ceiling sleeve supervisory relay CS and the cut'ofi relay CC of the line circuit L; The relay CS de-energizing opens its alternate contact 27, allowing the link disconnect relay LD and relay CS to restore. The answering sleeve supervisory relay AS is also de-energized and brings about the eltaceincnt or the supervisory lamps AL and CL. The relays LD and AS upon'de-ener'gizing restore the aparatus in the cord circuit C to normal, placing it in condition for use in establishing other connections.

Should the calling subscriber at the substation A desire to recall. before the plugs have been removed from the respective acks J and J, the removal oi the receiver the subscriber at the substation A again brings about the energization o1 the line relay LR, and the line relay LR upon energization closes its alternate contact. 2 to light the multiple line lamps S that appear at the differ nt operators positions in the exchange switchboard, and any one of a plurality of operators may seize the recall.

Assuming now that the subscriber at the substation A and the subscriber at the substation arein conversation, as before described, and' that another subscriber in the I exchange wishes to converse with the sub-v scriber at the substation B. The operator who now attempts to establish the connection tests the multiple ack J of the wanted substation B. Assinning she receives but does not heed the busy click received, and inserts the calling plugCP of her cord pair into the busy multiple jack J associated first connected cord circuit C, through 'alternate contact 33 of the relay CS, conductor 32, sleeve contacts of the connected plug GP and jack J, to ground "through the winding of the cut-off relay CO. The.

high resistance winding 31 of the relay GS of the first cord C is shunted out, and the.

calling sleeve supervisory relay GS of the second cord that has :now been connected to the multiple jack J of the busy line as+' sociated with the substation B will not operate in series with cutbii relay CO, as; the shunt or" the low Winding 30 of the calling sleeve supervisory relay GS of the cord circuit C renders the calling sleeve supervisory relay GS of the second cord inoperative, as the said relay GS ofthe second cord will not receive suificient current to operate-it and the relay GS of the'second cord failing to energize, its-alternate contact 27 is not closed. Therefore, no energizing circuit is'established for the secondary sleeve supervisory relay GS of the second cord, and the relay GS of the second cord failing to energize, its alternate contact remains open and thus the tip conductor of the second cord circuit that is new connected with the multiple jack J of thesub station B is open at th-is'point and prevents the subscriber that is trying for a connec-' tion with the substation B, from listening in on the conversation, eventhough the calling plugCP oi thesecond cord has been in-- serted in a multiple jack J associated with the now talkingsubscriber at the substation From the foregoing it may be seen that the system of my lnvention provides absolute secret service, thus preventing any sub scriber from being connected in circuit with two talking subscribers and listening in on the conversation.

Assuming a third subscriber wishes to converse with the calling subscriber at the substation A after the said subscriber'has been placed in conversational circuit with.

another substation and the operator attempting to establish this connection passes the busy test on the multiple jack J of the calling line. The answering sleeve relay AS of the cord that already connected is provided with a low resistance series circuit with the cut-ofl relay C0 of the substation A and this low resistance path will operate the calling sleeve'relay GS of the second irom'operating for the same reasons as already stated, and it is therefore seen that the subscriber attemptingto establish a call with the; now talking subscriber at substation A is prevented from listening in.

While lhaveillust-rated and described my inventionain connection with a specific circuit arrangement, I wish it understoodthat my invention is applicable to circuits other than that shown. Changes and modifications Will also readily suggest themselves to those skilled in th'e'art, and I therefore do not wishtobe limited to the exact structure shown, but aim to cover. all such changes and modifications as come within the spirit and scope of theappended claims.

What I claim as new and desire to secureby UnitedStates LettersPatent, is:

l. A telephone system including calling and called subscribers lines; a plurality of connectionterminals for said lines, busying cuits for connectingto said terminals to interconnect. said lmes, an operators telephone means for busying said connection terminals, when connections are made thereto, link C1l V set adapted-to be "connected toand disconnected' from any one of said link circuits,

ing end of-said link circuits whereby when and" individual means included in the callone of said link circuits is connected to" a connection terminal of a called line a second one of said link circuits cannot be operativelyconnected to another terminal'of the same called line, said means including a relay having a low resistance and a.high resistance winding, and which relayfthrough its own contacts disconnects said operatorssetvfrom said link circuit. V 2. A telephone system including'calling and called subscribers: lines, a plurality of ice 7 connection terminals for each of said lines,

operators. :link' circuits for interconnect-ing saidrlines, busying means for busying'said connection-terminals when connections are 1 made thereto individual means incl'uded in the calling end of said link circuits whereby when onegofsald link clrcults 18 connected to, a connection terminal of a called line a second-joneot said link circuits cannot, be

a relay having a high resistance and a low resistance winding, an operators telephone set common to said. link circuits but normally disconnected therefrom,and a circuit including contacts of said relay for connecting anddisconnecting saidioperators set and said link circuits,'saidjlast circuit forming apart of thetalking circuit between said set, and said link circuits. l

operators 3. A telephone system including calling and calledsubscribers lines, a plurality of connectionterminalsfor each voffsaid lines, 7 a

operators link circuits for interconnecting 115 .operatively connected to another terminal of the said called line, said means including said lines busying means for busying said terminals when connections are made thereto, a sleeve relay tor the calling end of said link circuit having a. high stance and low resistance winding and contacts for said relay for short-circuiting said high resistanie winding when connection is made with a called line to establish a low resistance circuit for said relay, a second relay controlled operators link circuits for interconnecting said lines busying means for placing abusy potential upon said conn ction terminals when connections are made thereto, a sleeve relay associated with the calling end or the link circuit having a high and low resistance winding contacts for said relay for shortcircuiting said high resistance winding when connection is niadewith a called line; whereby when said link circuit is connected to a called line a second one of said link circuits cannot be operatively connected to another terminal of the same called line due to the low resistance winding of said sleeve relay out the first link circuit that is connected, automatic means for registering the number of calls answered, and a circuit for said automatic means including a contact oi said sleeve relay.

' 5 A telephone system including calling and called subscribers lines, a plurality of connection terminals for each. 0t said lines, operators link circuits for interconnecting said linesybusying means for placing a busy.

potential upon said connect-ion terminals, an individual sleeve relay associated with the calling end of said link circuits having a high resistance and low resistance winding, contacts for said relay for short-circuiting said. highresistance Winding when connection is made with. a called line, whereby. when said link circuit is connected. to a called line a. second one of said link circuitscannot be operatively; connected to another terminal of the same called line as the low resistance path of the first link circuit, prevents the sleeve relayl of the second; link cir cuitfrom operating, a second relay controlled by said sleeve relay for controlling contacts in the conductors of the said'link circuitS autoniatic means for recording the number or calls answered, andaxcircuit' for; said automatic means including a contact or said sleeve relay 6. A telephone system including calling and called subscribers lines,, a; plurality of connection terminals for each; of said lines;

operators. link. circuits for interconnecting;

said lines, busyinglneansfor placing a busy. potential'upon said connection-terminals, a sleeve relay associated with the calling-end of said linkcircuithavinga high and low'resistance winding, contactsafor-said relay for short-circuiting said high resistance wind- *ing whenconnection is made with a called line,, asecond relay controlled by saidsleeve relay'forcontrolling the continuity o1 the link conductor of the said'link circuit, a low resistance path for said sleeve relay whereby when said link circuit is connected'fto said" called line a second one of said link circuits cannot cooperatively; connected to another terminal of the same called line as the low resistance path of the sleeve relay of the'first link circuit prevents the sleeve relay of the second link circuit from operating and the second relay of the second link circuit thus; remains at normal preventing the closingof normally open contacts in thelink conductors of thesecond link circuit, an operators, telephone set for said link circuits but nor mally disconnected therefronnand a circuit including contacts. of said sleeve relay for;

connecting. and disconnecting said operators set and said first link circuit.

Signed by me at Chicago, in the county of Cook and State of 1llinois,.this'17th-day-of 7 June 1921.

JOHN ELHILBISHZ 

